Where to Place DAs

This section provides suggestions for where to place DAs in different
situations.

When multicast routing is not enabled and DAs are required
to bridge service discovery between subnets

In this situation,
a DA must be placed on a host with interfaces and all subnets that share services.
The net.slp.interfaces configuration property does not need to be set, unless IP packets are not routed among the interfaces.
See Multihoming Configuration for SLP for
more information on configuring the net.slp.interfaces property.

When DAs are deployed for scalability and the primary consideration
is optimizing agent access

UAs typically make many requests for
services to DAs. An SA registers with the DA once, and can refresh the advertisement
at periodic but infrequent intervals. As a result, UA access to DAs is far
more frequent than SA access. The number of service advertisements is also
usually smaller than the number of requests. Consequently, most DA deployments
are more efficient if the deployment is optimized for UA access.

Situating DAs so that they are topologically close to UAs
on the network to optimize UA access

Naturally, you must configure
the DA with a scope that is shared by both the UA and SA clients.

Placing Multiple DAs for Load Balancing

You can deploy multiple DAs for the same collection of scopes as a means
of load balancing. Deploy DAs in any of the following circumstances:

UA requests to a DA are timing out, or are returning with the DA_BUSY_NOW error.

The DA log shows that many SLP requests are being dropped.

The network of users who share services in the scopes spans
a number of buildings or physical sites.

You can run a snoop trace
of SLP traffic to determine how many UA requests return with the DA_BUSY_NOW error. If the number of UA requests returned is high, UAs in buildings
physically and topologically distant from the DA can exhibit slow response
or excessive timeouts. In such a scenario, you can deploy a DA in each building
to improve response for UA clients within the building.

Links that connect buildings are often slower
than the local area networks within the buildings. If your network spans multiple
buildings or physical sites, set the net.slp.DAAddresses property
in the /etc/inet/slp.conf file to a list of specific host
names or addresses so that the UAs access only the DAs you specify.

If a particular DA is using large amounts of host memory for service
registrations, reduce the number of SA registrations by reducing the number
of scopes the DA supports. You can split into two a scope that has many registrations.
You can then support one of the new scopes by deploying another DA on another
host.